Research on the Relationship Between Effective Porosity and Permeability Coefficient in Permeable Concrete with Composite Admixtures

With China actively promoting the construction process of "sponge cities", permeable concrete urgently needs further development. This article obtains the macroscopic effective porosity and permeability coefficient through macroscopic permeability tests, and the microscopic effective porosity and permeability coefficient through microscopic X-CT tests. Fit the experimental results to obtain the relationship between macro effective porosity and permeability coefficient function, and the relationship between micro effective porosity and permeability coefficient. Based on the constant uniform pressurized laminar flow pipeline model and the Blick nonlinear laminar flow pipeline model, the relationship formula obtained from the validation fitting is reliable. Through analysis, it is concluded that the critical value of seepage state change inside pervious concrete is that the area proportion of nonlinear seepage holes should reach 75 %, and the number proportion of nonlinear seepage holes should exceed 11 %. Under this condition, a nonlinear laminar flow system similar to network structure will be formed inside pervious concrete, thus significantly improving the permeability.